.\" Copyright (c) 2019, Oracle.  All rights reserved.
.\"
.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
.\" SPDX-License-Identifier: GPL-2.0+
.\" %%%LICENSE_END
.TH IOCTL-XFS-AG-GEOMETRY 2 2019-08-30 "XFS"
.SH NAME
ioctl_xfs_ag_geometry \- query XFS allocation group geometry information
.SH SYNOPSIS
.br
.B #include <xfs/xfs_fs.h>
.PP
.BI "int ioctl(int " fd ", XFS_IOC_AG_GEOMETRY, struct xfs_ag_geometry *" arg );
.SH DESCRIPTION
This XFS ioctl retrieves the geometry information for a given allocation group.
The geometry information is conveyed in a structure of the following form:
.PP
.in +4n
.nf
struct xfs_ag_geometry {
	uint32_t  ag_number;
	uint32_t  ag_length;
	uint32_t  ag_freeblks;
	uint32_t  ag_icount;
	uint32_t  ag_ifree;
	uint32_t  ag_sick;
	uint32_t  ag_checked;
	uint32_t  ag_flags;
	uint64_t  ag_reserved[12];
};
.fi
.in
.TP
.I ag_number
The caller must set this field to the index of the allocation group that the
caller wishes to learn about.
.TP
.I ag_length
The length of the allocation group is returned in this field, in units of
filesystem blocks.
.TP
.I ag_freeblks
The number of free blocks in the allocation group is returned in this field, in
units of filesystem blocks.
.TP
.I ag_icount
The number of inode records allocated in this allocation group is returned in
this field.
.TP
.I ag_ifree
The number of unused inode records (of the space allocated) in this allocation
group is returned in this field.
.TP
.I ag_flags
The caller can set this field to change the operational behavior of the ioctl.
Currently no flags are defined, so this field must be zero.
.TP
.IR ag_reserved
All reserved fields will be set to zero on return.
.PP
The fields
.IR ag_sick " and " ag_checked
indicate the relative health of various allocation group metadata:
.IP \[bu] 2
If a given sick flag is set in
.IR ag_sick ,
then that piece of metadata has been observed to be damaged.
The same bit will be set in
.IR ag_checked .
.IP \[bu]
If a given sick flag is set in
.I ag_checked
and is not set in
.IR ag_sick ,
then that piece of metadata has been checked and is not faulty.
.IP \[bu]
If a given sick flag is not set in
.IR ag_checked ,
then no conclusion can be made.
.PP
The following flags apply to these fields:
.RS 0.4i
.TP
.B XFS_AG_GEOM_SICK_SB
Allocation group superblock.
.TP
.B XFS_AG_GEOM_SICK_AGF
Free space header.
.TP
.B XFS_AG_GEOM_SICK_AGFL
Free space reserve list.
.TP
.B XFS_AG_GEOM_SICK_AGI
Inode header.
.TP
.BR XFS_AG_GEOM_SICK_BNOBT " or " XFS_AG_GEOM_SICK_CNTBT
Free space btrees.
.TP
.BR XFS_AG_GEOM_SICK_INOBT " or " XFS_AG_GEOM_SICK_FINOBT
Inode btrees.
.TP
.B XFS_AG_GEOM_SICK_RMAPBT
Reverse mapping btree.
.TP
.B XFS_AG_GEOM_SICK_REFCNTBT
Reference count btree.
.RE
.SH RETURN VALUE
On error, \-1 is returned, and
.I errno
is set to indicate the error.
.PP
.SH ERRORS
Error codes can be one of, but are not limited to, the following:
.TP
.B EFSBADCRC
Metadata checksum validation failed while performing the query.
.TP
.B EFSCORRUPTED
Metadata corruption was encountered while performing the query.
.TP
.B EINVAL
The specified allocation group number is not valid for this filesystem.
.TP
.B EIO
An I/O error was encountered while performing the query.
.SH CONFORMING TO
This API is specific to XFS filesystem on the Linux kernel.
.SH SEE ALSO
.BR ioctl (2)
